Do you mean thread size?
D4's are all the same 1-1/8" x 12tpi.
Identification depends on whether they are two piece (chamber & retainer) or one piece type. Cylinder head bore for chambers is a smaller diameter for early heads (yours). Later large bore chambers are a hair over 2-3/8" dia. Early units are slightly over 2-1/8 dia.
Best to go by part numbers and don't trust after market lists as they are full of errors.
[quote="Old Magnet"]D4's are all the same 1-1/8" x 12tpi.
Identification depends on whether they are two piece (chamber & retainer) or one piece type. Cylinder head bore for chambers is a smaller diameter for early heads (yours). Later large bore chambers are a hair over 2-3/8" dia. Early units are slightly over 2-1/8 dia.
Best to go by part numbers and don't trust after market lists as they are full of errors.[/quote]
Thanks for the replies. Hasting Deering (Caterpillar Aus) never got back to me so I went through Tilly's Crawler parts and he said there were two different sizes so I take it mine is the earlier and smaller size? Not sure what year mine is.
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